I followed this instructions on how to work with subcontracting processes but it does not work as we expect.

https://www.odoo.com/es_ES/slides/slide/subcontracting-856?fullscreen=1

So we have a product that is manufactured in our facilities (lets call it Product A), but then it is sent to a paining process outside of our company (so when it comes back it would be called Product B), and later that same product returns to our facilities to be assembled (so Product B is mounted in Assembly A).

What I'm doing:

1 - Create Product A. Set its reordering rules as 0, 0, 1. Set its own BOM. Set its routes as 'Manufacture' and 'Ressuply on Subcontor on Order'. Disable 'Can be bought' and 'Can be sold'.

2 - Create Product B. Set its reordering rules as 0, 0, 1. Set its own BOM. Set its routes as 'Buy' only. Enable 'Can be bought' and 'Can be sold'. 

3 - Create Product Bs BOM. Set Product A as a part of Product B. Set 'Subcontracting' and adding a valid Company A as subcontractor.

Just for testing I stopped here (without including Product B in Assembly A) and simulated several SO from our customers of Product B, but then it only triggers a buying order to Company and there is no need for me to deliver anything to them neither MO for Product A are triggered...

I have also tried changing Product A configuration setting its routes to 'Buy? and 'Ressuply on Subcontor on Order' without any success.

What am I doing wrong? Is subcontracting intended to work that way?

Thank you.